Field of the Invention
The present invention relates to methods for degrading or converting cellulosic material and enzyme composition for degrading or converting cellulosic material.
Description of the Related Art
Catalases [hydrogen peroxide: hydrogen peroxide oxidoreductases (EC 1.11.1.6)] are enzymes which catalyze the conversion of hydrogen peroxide (H2O2) to oxygen (O2) and water (H2O). These ubiquitous enzymes have been purified from a variety of animal tissues, plants and microorganisms (Chance and Maehly, 1955, Methods Enzymol. 2: 764-791).
Catalase preparations are used commercially for diagnostic enzyme kits, for the enzymatic production of sodium gluconate from glucose, for the neutralization of H2O2 waste, for removal of H2O2 from textile fabrics, and for the removal of H2O2 and/or generation of O2 in foods and beverages.
Cellulose is a polymer of simple sugars covalently linked by beta-1,4-bonds. Many microorganisms produce enzymes that hydrolyze beta-linked glucans. These enzymes include endoglucanases, cellobiohydrolases, and beta-glucosidases. Endoglucanases digest the cellulose polymer at random locations, opening it to attack by cellobiohydrolases. Cellobiohydrolases sequentially release molecules of cellobiose from the ends of the cellulose polymer. Cellobiose is a water-soluble beta-1,4-linked dimer of glucose. Beta-glucosidases hydrolyze cellobiose to glucose.
The conversion of lignocellulosic material has the advantages of the ready availability of large amounts of feedstock and the desirability of avoiding burning or land filling the materials. Wood, agricultural residues, herbaceous crops, and municipal solid wastes have been considered as feedstocks. These materials primarily consist of cellulose, hemicellulose, and lignin. Once the lignocellulose is converted to simple sugars, e.g., glucose, the simple sugars can further be converted to many useful substances, e.g., fuel, potable ethanol, fermentation products and/or chemicals (e.g., acids, alcohols, ketones, gases, and the like).
It would be advantageous in the art to improve methods for degrading or converting a cellulosic material.